Radiation mask for the lithographic production of patterns

ABSTRACT

A radiation mask for the lithographic production of patterns, particularly for the X-ray lithographic or ionic lithographic production of semiconductor modules and semiconductor components and of optical grids. The radiation mask includes a carrier layer mounted in a support frame. The carrier layer has a structure corresponding to the pattern to be created. The carrier layer has in its border portion between the structure and the support frame an elastic portion. This elastic portion serves to ensure dimensional accuracy of the structure when stresses occur. The elastic portion may be formed by perforations defined in the carrier layer circumferentially surrounding the structure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radiation mask for the lithographicproduction of patterns. The radiation mask includes a carrier layermounted in a support frame. The carrier layer defines a structurecorresponding to the pattern to be created.

2. Description of the Prior Art

A radiation mask of the above-described type is used particularly forthe X-ray lithographic or ionic lithographic production of semiconductormodules and semiconductor components and of optical grids.

Radiation masks for the X-ray lithographic production of patterns areknown from German Offenlegungsschrift No. 32 32 499 and GermanOffenlegungsschrift No. 34 27 449. These masks include a radiationpermeable carrier layer mounted in a support frame. The carrier layerhas a radiation absorbing structure which corresponds to the pattern tobe created.

A radiation mask of the same type for X-ray lithography or ioniclithography is described in German Offenlegungsschrift No. 31 50 056.The support frame for the radiation permeable carrier layer of the maskhas markings for the optical alignment of the radiation mask relative tothe semiconductor substrate to be irradiated.

Since a high resolution of the pattern to be created can be achievedparticularly by means of X-ray lithography, an extremely highdimensional accuracy of the structure of the radiation maskcorresponding to the pattern to be created is absolutely required.

In the manufacture and the use of such a radiation mask, variable stresscomponents occur for various reasons, for example, due totemperature-related loading of the carrier layer with the structureduring irradiation or due to deformations of the carrier layer with thestructure caused by improper fastening in the support frame. Thesevariable stress components may lead to non-reproducible lateraldistortions of the carrier layer, so that the dimensional accuracy ofthe radiation mask is no longer ensured.

German Offenlegungsschrift No. 34 25 063 discloses a radiation mask forX-ray lithography in which such lateral mechanical distortions areavoided by means of a stress-compensated carrier layer. This carrierlayer is a silicon layer doped with two different materials to achievethe stress compensation. However, this type of stress compensationrequires specific materials. In addition, a radiation mask with thistype of stress compensation is difficult to manufacture.

It is, therefore, the primary object of the present invention to providea radiation mask of the above-described type in which the dimensionalaccuracy of the structure is maintained during the occurrence of stresscomponents.

SUMMARY OF THE INVENTION

In accordance with the present invention, the carrier layer of theradiation mask has an elastic portion in the border region thereofbetween the structure and the support frame.

The particular advantage of the radiation mask according to the presentinvention resides in that the elastic portion in the border region ofthe carrier layer between the structure and the support frame leads in asimple manner to a compensation of occurring stress components.

The elastic portion of the carrier layer may be formed by at least tworows of perforations which surround the portion with the structure.These perforations can be easily manufactured. In addition, there are noconstraints with respect to the materials suitable as carrier layers.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the drawings and descriptive matter in whichthere is illustrated and described a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is a sectional view of the radiation mask according to thepresent invention; and

FIG. 2 is a plan view of the radiation mask of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 of the drawing is a cross-sectional view and FIG. 2 of thedrawing is a top view of the radiation mask according to the presentinvention. The radiation mask is used for lithographically producingpatterns having high resolutions, particularly of optical grids and ofsemiconductor modules and semiconductor components by means of X-raylithography or ionic lithography.

A circular ring-shaped support frame 1, for example, of invar, supportsa radiation absorbing carrier layer 2, for example, of nickel. Carrierlayer 2 is fastened in support frame 1 by means of a clamping ring 3 andscrews 4. Carrier layer 2 is fastened in support frame 1 with a certaininitial tension to prevent sagging of the carrier layer 2 and to ensureplaneness of the carrier layer 2 in the inner portion 5 of support frame1.

In the inner portion 5 of support frame 1, carrier layer 2 has astructure portion 7 with a radiation permeable structure 8 obtained byphotolithographic means.

When the carrier layer 2 is fastened in the support frame 1 by means ofclamping ring 3, stress components may occur in the carrier layer 2which may lead to non-reproducible lateral distortions in the carrierlayer 2, so that the dimensional accuracy of structure 8 in structureportion 7 of the carrier layer 2 of the radiation mask is no longerensured. Such variable stress components may also occur during the useof the radiation mask due to temperature-related loading of the carrierlayer 2 during the irradiation.

For the compensation of such stress components, it is proposed inaccordance with the present invention to provide the border portion 9 ofcarrier layer 2 with an elastic portion 10 between the structure portion7 including structure 8 and the support frame 1. This elastic portion 10is formed by perforations 11 defined in carrier layer 2. Theseperforations 11 surround the structure portion 7 including structure 8in at least two rows.

In the preferred embodiment of the present invention illustrated inFIGS. 1 and 2, perforations 11 surround structure portions 7 includingstructure 8 in two rows in which the perforations of the two rows arecircumferentially offset relative to each other. The perforations 11 areoblong in circumferential direction. As a result of this configuration,the perforations 11 form spring elements which isolate the structureportion 7 including structure 8 from the stress components which emanatefrom support frame 1 and clamping ring 3.

The radiation mask may also include a radiation permeable carrier layer,not shown, mounted on the radiation absorbing structure. A radiationmask of this type is described, for example, in GermanOffenlegungsschrift No. 34 27 449.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

I claim:
 1. In a radiation mask for the lithographic production ofpatterns, including a carrier layer mounted in a support frame, thecarrier layer having a structure corresponding to the pattern to becreated, the improvement comprising an elastic portion defined in thecarrier layer in the border portion thereof between the structure andthe support frame whereby the dimensional accuracy of the structure ismaintained during the occurrence of stress components.
 2. The radiationmask according to claim 1, wherein the elastic portion includesperforations defined in the carrier layer.
 3. The radiation maskaccording to claim 2, wherein the perforations are provided in at leasttwo circumferentially extending rows.
 4. The radiation mask according toclaim 3, wherein the perforations of the at least two rows ofperforations are circumferentially offset relative to each other.
 5. Theradiation mask according to claim 1, wherein the carrier layer is of aradiation absorbing material and the structure is of a radiationpermeable material.
 6. The radiation mask according to claim 1, whereinthe carrier layer is of a radiation permeable material and the structureis of a radiation absorbing material.